Introduction. The model of an assessment of probability of casual combination of sets of routes in secondary traces is considered in article. Development of quantitative criteria of justification of a categorical positive conclusion about criminalistic identity of the compared traces, and also algorithm of formation in the automatic mode of the priority list is the purpose of the conducted research. Theoretical part. Twodimensional images of traces of rifling fields used for the simulation. The formulas for estimating the probability of an accidental match of trails were obtained. Experimental part. Calculations performed on the developed formulas, the dependence of the probability of an event compared to the number of trails should be shown. Conclusion. The theoretical possibility of estimating the probability of a random alignment sets of trails (the degree of matching features unique complexes) and its use in practice is shown in this paper.